The present invention disclosed herein relates to a time amplifier and a method of controlling the same.
Although CMOS technology scaling accompanies positive aspects such as performance improvement of a digital circuit and miniaturization due to the high degree of integration, analog circuit designers have experience difficulties in designing a circuit design due to gradually decreasing VDD. As an alternative to this, in relation to a typical method of obtaining information through an analog to digital converter (ADC) by carrying the information in voltage, a method of obtaining information through a time to digital converter (TDC) by carrying the information in time has been suggested recently. Such a TDC may include a time amplifier block. The time amplifier affects the resolution of the TDC greatly.
A typical time amplifier uses the metastability of a transistor basically. A metastability state of a transistor occurs when voltage is not sufficiently supplied to the gate of the transistor and this should be avoided in a typical digital circuit. In a metastability state, a current of the transistor represents the form of an exponential function, that is, a non-linear function. Accordingly, when a typical time amplifier amplifies a time difference (i.e., an input value) between two input signals by using the metastability of a transistor, because of non-linear operational characteristics of the transistor, a range of an available input value is limited greatly. Additionally, due to such non-linear operational characteristics, it is difficult for a typical time amplifier to maintain a time amplification gain constantly within a corresponding input range when an input range becomes broader.